Biomedical subjects

S Luo

Publications and source records attributed to S Luo.

At least 163 records · Page 9Linked to original sources

PubMed1995

Demonstration of in vitro cultured exoerythrocytic schizonts and hypnozoites of Plasmodium vivax (southern China isolate) by an immunoperoxidase antibody technique.

By indirect immunoperoxidase staining, different forms of exoerythrocytic (EE) stage of Plasmodium vivax (Southern China isolates) are revealed in d8 cultured material. The mature schizonts are elongated in shape measuring 42-48 microns in diameter, immature schizonts 14-28 microns and hypnozoites 4-7 microns. EE schizonts are stained dark-brown only after conjugated by monoclonal antibody (McAb) 4B2 specific against erythrocytic stages of P. vivax while hypnozoites are only stained after conjugated by McAb 2F2 against sporozoite. These results show that the antigenic components of these two forms of EE plasmodia are quite different. The ratio of EE schizont and hypnozoite found within hepatoma cells (HepG2-A16) is 1.5 to 1. Referred to the clinical manifestations of the isolate, among 5 volunteers not radically cured, two had long incubation period (283 d and 304 d, respectively) and three relapsed 235, 260 and 365 days after the primary attack. These data are unanimous with the comparatively large ratio of hypnozoites in the cultured material.

Animals↗

PubMed1995

[Research on the factors influencing the sporogonic multiplication of Plasmodium vivax in the mosquito vector].

Volunteers with no previous malaria history infected with northern Guangdong isolate of Plasmodium vivax and mosquito vector, Anopheles stephensi, were the objects and materials used in the research. Totally there were 16 volunteers, half of them were infected by mosquito-bite and another half by blood-inoculation. Blood was drawn when parasitemia reached a certain level and the erythrocytic forms developed into large trophozoites. Mosquitoes fed on infected blood from 5 and 4 donors of the two groups gave high gland infection rate and high gland indices respectively, but the highest gland indices were got from volunteers infected by mosquito-bite. The time of blood-feeding is important, only those blood samples taken from the people 3 to 8 days after the first onset gave good sporozoite harvest and the gland infection was greatly reduced on the 9th day. During this period (d3-8), the density of gametocyte had obvious influence on the intensity of mosquito infection. When the sex ratio of gametocyte (female:male) was 4:1 or less, the result would be good. For the purpose of reflecting more perfectly the circumstance of the sporogonic multiplication of plasmodium in the mosquito vector, we suggest the concept of gut/gland infection intensity which equals the product of the infection rate and the index of oocyst/positive gland.

Adult↗

PubMed1995

[Experience in management of capsular contraction through areolar incision after implantation of prosthesis for augmentation mammaplasty].

Since 1990, 19 cases of capsular contraction of Baker's III, IV have been treated with partial excision of the capsule and replacement of implants through areolar incision. The result was satisfactory. After six months to eighteen months follow-up observation, no capsular contraction was again found. All patients were graded Baker's I. Prevention of capsular contraction was also discussed.

Adult↗

PubMed1995

[Clinical application of thoraco-umbilical skin flap].

Since 1987 we have successfully used thoraco-umbilical skin flaps as free transplants to repair 8 cases of severe burn scar deformities of jaw-neck and hand regions, thoraco-umbilical insular skin flaps to each case of congenital vaginal atresia, severe vulval scar due to sulfuric acid burn and large penal tissue defect accompanied with severe urethral leakage. This flap has the following advantages: namely definite anatomical position, larger vascular diameter, fight large skin flap area, and similar skin completion as that of the jaw-neck region. Therefore they are the ideal substitute for the repair of soft tissue defects of jaw-neck region as well as extremities. The flap has long vascular pedicle, abundant vascularization, easy transportation and it is suitable to be a retrograde insular flap for repairing of vulval tissue defect, reformed penal vaginoplasty.

Adolescent↗

PubMed1995

[153Sm-EDTMP for moderate and severe bone cancer pain].

One hundred and thirty-six patients with bone cancer pain were treated with 153Sm-EDTMP (ethylenediamine-tetramethylene phosphonic acid). Pain free was noted in 49 cases (36%, 49/136) and pain relief in 77 cases (56.6%, 77/136), the total relief rate being 92.6% (126/136). The data from 76 patients with moderate and severe pain showed there were no significant relationships between the patients' age, the dose of 153Sm-EDTMP and the analgesic effects (P > 0.05). The pain relief observed in the patients with chest pain (ribs metastases) was earlier than that in other groups (P < 0.05). We didn't find any clinical side-effects, so 153Sm-EDTMP is safe for use.

Adult↗

PubMed1995

Effect of monoclonal antibodies on the entry and development of Plasmodium vivax sporozoite in cultured cells.

We have observed the effect of monoclonal antibodies against sporozoites (2F2,NV3,2E10) and blood stages (4B2,8E3) of P. vivax on entry and subsequent development of P. vivax sporozoites in HepG2--A16 cells in vitro. The results demonstrated that inhibitory effects of monoclonal antibodies on the attachment and entry were found to be related to the antibody concentration. At 25 micrograms/ml, the percentages of inhibition of sporozoite invasion were 100% (2F2), 76%(NVS3) and 10.5% (2E10). Even if the invasion was not totally inhibited, the presence of abnormal exoerythrocytic schizonts suggested that continued effect of antibodies after sporozoite penetration still existed. No significant effects of 4B2 (4.5%) and 8E3 (3.4%) were recorded as compared with normal mouse serum. These findings indicate that inhibition of sporozoite invasion assay may be useful for determining the protective effect of anti-sporozoite antibodies in vitro.

Animals↗

PubMed1995

[Alternation of intracellular Ca2+ caused by streptomycin in the isolated cochlear OHC].

Stained with fluorescence, the intracellular free calcium concentration (Ca2+) of the cochlear out hair cell (OHC) isolated from guinea pigs was measured using ACAS 570. Streptomycin caused a remarkable rise in Ca2+ and reached peak value in 60s, decreased gradually after lasting for 60s in that value. The Ca2+ fell back to primary level in another 100s and followed by a slight drop. The distribution of free calcium in the OHC was showed. The rise of intracellular free calcium in the OHC was assumed to be a period in the ototoxicity caused by aminoglycoside antibiotics.

Animals↗

PubMed1994

Use of photoacoustic Fourier-transform infrared spectroscopy to study phosphates in proteins.

Photoacoustic Fourier-transform infrared spectroscopy was used to study phosphoamino acids and phosphoproteins. Using this method, we have found that the spectral properties of phosphate esters depend on the nature of the linkage, pH, and binding of metal ion. At high pH values, dianionic symmetric stretching of phosphotyrosine and phosphoserine occurs at 984 and 974 reciprocal centimeters, respectively. Analysis of the IR bands of bound phosphate in phosvitin at different pH values gives the pKa value for the esterified phosphates. Addition of aluminum ions to phosvitin at different pH values causes a shift in the phosphate band consistent with a direct binding of aluminum ions to the esterified phosphate. The phosphate signal for 40 micrograms of Pepsin (1 P/mole) is detectable by this method.

Acoustics↗

PubMed1994

Mutational analyses of the metal ion and substrate binding sites of phosphorylase kinase gamma subunit.

Phosphorylase kinase (PhK) and truncated gamma subunit, denoted gamma 1-300, can phosphorylate seryl and tyrosyl residues dependent on the metal ion [Yuan, C.-J., Huang, C. F., & Graves, D. J. (1993) J. Biol. Chem. 268, 17683-17686]. Recombinant gamma 1-300 was used to explore its dual specificity and the location of the metal ion binding sites by using site-directed mutagenesis. Two approaches were taken to generate 26 mutants. First, on the basis of the crystal structure of cAMP-dependent protein kinase (cAPK), the invariant Asn155 and highly conserved Asp168-Phe169-Gly170 residues were mutated. Changes included production of N155H, D168E, D168N, F169R, G170V, G170I, G170L (less than 1% of enzymatic activities were found in these mutants), F169W, and G170A mutants. Second, charge to alanine and charge reversal scanning mutations were used to probe the metal ion binding sites. Two mutants, E111K and E154R, showed very different metal ion response compared to wild-type gamma and were further characterized. The mutants F169W, G170A, E111K, and E154R had 15%, 5%, 8%, and 25% specific activity relative to wild-type gamma, respectively. The folding pattern of wild-type and mutated enzyme forms of gamma was determined by photoacoustic infrared spectroscopy. Conformational disruptions were found in G170V, G170I, and G170L mutants, but the conformation of the rest of the mutants was similar to that of wild-type gamma, suggesting that the loss of enzymatic activities of these mutants was not because of incorrect refolding.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1994

A study of protein secondary structure by Fourier transform infrared/photoacoustic spectroscopy and its application for recombinant proteins.

FT-IR/PAS (Fourier transform infrared/photoacoustic spectroscopy) was used to evaluate the secondary structure of proteins. Four well-studied proteins, concanavalin A, hemoglobin, lysozyme, and trypsin, which have different distributions of secondary structures, were used for assignments of the infrared bands and evaluating the accuracy of FT-IR/PAS methods. Secondary structure contents estimated from FT-IR/PAS and other physical methods (e.g., X-ray diffraction, CD, and traditional FT-IR) show good agreement. In addition, the secondary structure can be evaluated with as little as 0.5 micrograms of protein (concanavalin A), suggesting that FT-IR/PAS is a sensitive and useful technique that could be applied to studies of the folding of recombinant and mutant proteins where only small amounts of material are available. Recombinant phosphorylase kinase gamma 1-300 subunit expressed in Escherichia coli was found in the inclusion bodies. We found that renatured phosphorylase kinase gamma 1-300 subunit has two kinase forms: one has a 10-fold higher activity than the other one. Both fractions, however, are the same as judged from sodium dodecylsulfate-polyacrylamide gel electrophoresis. Differences in conformation were demonstrated by using the FT-IR/PAS method, which showed that the low-activity form has more beta-sheet structure than the form with high activity. Analysis of these kinase forms by CD confirms the interpretation made by the FT-IR/PAS method.

Protein Structure, Secondary↗

PubMed1994

Parameter evaluation of the inverse power-law spectrum of heart rate. A quantitative approach for ECG arrhythmia analysis.

A preliminary study was performed to ensure reliable R-wave detection and fiducial mark location. A generalized phase-sampling model for spectral estimation was then used, based on an interest in beat-to-beat variations. Heart rate spectrum characteristics of 32 presumed-normal subjects and 44 records from the MIT-BIH electrocardiographic database (Massachusetts Institute of Technology, Cambridge, MA) were analyzed and three parameters were calculated: regression line slope, intercept, and cross correlation between the spectral data and the regression lines. Evaluation of these inverse power-law spectrum parameters provides a potential quantitative approach for characterizing erratic fluctuations of heart rate and is possibly used to distinguish between healthy and abnormal subjects. From the 44 recordings in the MIT-BIH database, a V-shaped curve was found in a plot of the regression line slope versus cross correlation. The results for both unmedicated and medicated patients with normal sinus rhythm cluster in the top left region of the graph. Also, 29 of the presumed-normal subjects cluster in the same region. Patients with premature ventricular contraction beats cluster in the top right region of the V-shaped curve. The rest of the recordings from the variety of arrhythmia cases in the database have low slopes and cross correlations, so they cluster near the apex of the V-shaped curve. Three volunteers who each had more than 32 atrial premature contraction and premature ventricular contraction beats also fall in this region of the graph. The results from 10 young volunteers from the United States and 15 volunteers from seven other countries cluster into different regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Opposite effects of prolactin and corticosterone on the expression and activity of 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase in rat skin.

In rat skin, type IV is the major 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD) isoenzyme expressed. Although types I and II 3 beta-HSD mRNAs are also present in the skin, their level of expression is about two orders of magnitude lower than that of type IV. In this study, we have investigated the control of type IV 3 beta-HSD mRNA levels as well as 3 beta-HSD enzymatic activity in hypophysectomized adult rats of both sexes. Skin 3 beta-HSD activity was measured by the conversion of [14C]-dehydroepiandrosterone into [14C]-androstenedione, whereas ribonuclease protection assay using a specific type IV cRNA probe was used to assess mRNA levels. Intact male and female rats show a similar level of skin 3 beta-HSD activity, although hypophysectomy caused opposite effects, a decrease being observed in males while an increase was observed in hypophysectomized female animals. We next studied the effects of hyperprolactinemia, corticosterone and 1-thyroxine in hypophysectomized animals. L-thyroxine was found to stimulate 3 beta-HSD expression and activity in male rats whereas no significant effect was observed on the already elevated levels in hypophysectomized female rats. Corticosterone caused an inhibition of type IV 3 beta-HSD mRNA levels and activity in both male and female animals. Hyperprolactinemia achieved by pituitary implants inserted under the kidney capsule stimulated the expression of type IV mRNA as well as 3 beta-HSD enzymatic activity in hypophysectomized male and female animals. The present data demonstrate the multihormonal regulation of 3 beta-HSD/isomerase expression and activity in the rat skin.

Animals↗

PubMed1994

Effects of essential amino acids on food and water intake of rats.

This study examined the effects of selected groups of essential amino acids (EAAs), given by gavage, on short-term food and water intake. Amino acid groups were selected on the basis of their common physiologic functions in relation to current hypotheses on the role of amino acids in food intake control, and the quantities given were based on the proportions in 1.5 g of the EAA content of albumin. The complete EAA mixture (1.5 g) suppressed food intake by an average of 60 and 37% during the 1st and 2nd h of feeding, respectively, but had no influence on feeding in the subsequent 12 h. Total daily (14 h) intake was decreased by 9%. With the exception of the aromatic amino acid (Phe + Tyr + Trp, 0.34 g) group, all groups significantly decreased food intake by a comparable magnitude (32%) during the 1st h. In this time period, rats given the EAAs, Arg + Met + Val (0.38 g), and Arg + His + Lys (0.44 g) mixtures increased their water intake, whereas intake by rats given the Phe + Tyr + Trp + Thr (0.46 g) and Ile + Leu + Val (0.45 g) mixtures was unchanged. Thus, the food intake suppression caused by EAAs was not accounted for by an equal effect of its component amino acid groups. As well, food intake suppression by amino acid groups was not explained by increased water consumption, nor was it simply related to the quantity of nitrogen provided by the treatment.

Amino Acids, Essential↗

PubMed1994

(S)-linalyl, 2-phenylethyl, and benzyl disaccharide glycosides isolated as aroma precursors from oolong tea leaves.

Three glycosides, 6-O-beta-D-xylopyranosyl-beta-D-glucopyranosides (beta-primeverosides) of the aroma constituents, linalool, 2-phenylethanol, and benzyl alcohol, were isolated as aroma precursors from the tea leaves (Camellia sinensis var. sinensis cv. Shuixian and Maoxie, cultivars for oolong tea). The isolation was guided by acid or enzymatic hydrolysis, and subsequent GC and GC-MS analyses. The linalyl glycoside is the first example of naturally occurring (S)-linalyl beta-primeveroside.

Benzyl Alcohols↗

PubMed1994

trans- and cis-linalool 3,6-oxide 6-O-beta-D-xylopyranosyl-beta-D-glucopyranosides isolated as aroma precursors from leaves for oolong tea.

New glycosidic aroma precursors (1 and 2) of the main volatile constituents, trans- and cis-linalool 3,6-oxides (linalool oxides I and II), were isolated from oolong tea leaves (Camellia sinensis var. sinensis cv. Maoxie). The isolation was guided by an enzymatic hydrolysis with acetone powder prepared from fresh tea leaves (cv. Yabukita) followed by GC or GC-MS analyses. Chromatographic purification of hot water extracts of the tea leaves on active charcoal, Amberlite XAD-2, and Sephadex LH-20 columns as well as HPLC gave two new glycosides, trans- and cis-linalool 3,6-oxide 6-O-beta-D-xylopyranosyl-beta-D-glucopyranosides (1 and 2).

Acyclic Monoterpenes↗

PubMed1994

[Effect of crystal no. 4 of polygonum cuspidatum on the viability of island flaps with venous stasis: an experimental study].

The effects of crystal No. 4 of Polygonum cuspidatum on microcirculatory changes of island flaps in rats following resumption of blood flow after venous occlusion of six hours were observed with a special TV set with magnification of 500X. The pathological events and survival rate of flaps were recorded as well. The results showed that the survival rate, amount of open capillaries, amount of blood flow, and velocity of blood flow of flaps treated by crystal No. 4 of polygonum cuspidatum were much higher than those of untreated control flaps. The white thrombosis and endothelial damage of dermal vessels were alleviated by administration of crystal No. 4 of polygonum cuspsidatum. The experiment also showed that there were no differences between flaps treated with crystal No. 4 of polygonum cuspidatum preoperatively and flaps treated with it postoperatively.

Animals↗

PubMed1994

[In vitro cultivation of the exoerythrocytic stage of Plasmodium vivax (southern China isolate)].

An in vitro culture system for the exoerythrocytic (EE) stage of Plasmodium vivax was first developed in our laboratory in China. Anopheles stephensi mosquitoes were infected by membrane feeding with heparinized blood from a volunteer. After 14-18 days, the mosquito salivary glands were aseptically dissected in culture medium and ground in a tissue grinder to form sporozoite suspension. Sporozoites were counted and added to the cultures of monolayer hepatoma cells at the number of 4.9 x 10(4)-1.3 x 10(5) per cover glass. Sometimes, 8-10 pairs of infected gland were added directly to the cultured cells. On day 7, EE schizonts of P. vivax were found in cultures. In addition, normal erythrocytes (type o) were added to the cultures on day 10 at a concentration of 10(8) per dish. Fourteen days later, erythrocytes in culture supernatant were collected and thin blood films were made. Numerous intra-erythrocytic P. vivax parasites were identified on the films after Giemsa staining. Most intra-erythrocytic forms were rings and early large trophozoites. Schuffer's dots were present in many of the infected cells which were pale and obviously enlarged. These results indicated that the in vitro hepatic cycle of P. vivax was established.

Animals↗

PubMed1994

[Relationship between effect of sodium selenite on blocking mesothelioma induced by crocidolite and level of serum lipid peroxidation in rats].

This paper reports the relationship between the effect of sodium selenite on blocking mesothelioma induced by crocidolite and the level of serum lipid peroxidation in rats. The result showed that sodium selenite solution (5ppm) might not only block and slow down the formation and growth of mesothelioma but also prevent peroxidation produced by crocidolite. The incidence of mesothelioma and the content of LPO in the Se group were lower than those in the positive control group in different periods (0-430 days and 0-530 days respectively). The survival time (341 days) of the first case of mesothelioma and the death peak period (530-630 days) in the Se group were longer than those (237 days and 430-530 days respectively) in the positive group. There was a good correlation between the change of G value in the Se group and the change of G value in the positive control group in different experimental periods (r = 0.9991). These results will provide scientific bases for recognizing the mechanism of mesothelioma and for furthering the practice in the people exposed to asbestos.

Animals↗